1. Field of Invention
The present invention relates to apparatus for manufacturing tubes by helical coiling of a preferably corrugated strip, in particular a sheet metal strip, comprising coiling means equipped with two connecting means arranged at the strip-entering point and acting on a surface of the two strips to mutually join the adjacent convolution of the tube, then means to guide said joined strip in a circle to produce a next convolution.
2. Description of the Prior Art
A device of the aforedescribed class is already known (cf. German patent application laid open to public inspection DT-OS No. 2,453,876). This document discloses the means geared to move said strip in a circle to produce a convolution, which is composed of supporting rollers arranged at the periphery of the convolution to be produced and serving to guide same; these supporting rollers are paraxially arranged at a support for free rotation. To achieve a compensation for different values of strip thickness the supporting rollers can be geared for radial adjustment at the support, relative to their circular arrangement.
It has become apparent that the known devices cannot always produce tubes having exactly the desired tube diameters; this is true particularly for different strip qualities, and above all for different values of strip thickness or bending resistance. Since in one and the same strip deviations in quality cannot be avoided either, the diameters of the convolutions are frequently different, too, in tubes produced in the known devices.